In a plasma processing apparatus, wafers serving as a processing target are supported by a support stand called a susceptor provided in a chamber. Then, a high-frequency voltage is applied to a hermetically-sealed chamber and a plasma generating gas is supplied thereto to generate plasma in the chamber. The wafers are exposed to the plasma and plasma processing such as dry etching is thereby executed on the wafers.
According to such plasma processing apparatus, a plurality of wafers are collectively supported by the support stand, so that a tray capable of housing the plurality of wafers is used (Japanese Patent Laid-open Publication No. 2009-147375, for example). The tray has a plurality of housing holes each having a diameter a little larger than that of the wafer. The wafer is housed in each housing hole. The tray housing the wafers is carried by a carrying mechanism after aligned and then supported by the support stand. Each wafer in the tray is electrostatically absorbed by an electrostatic absorption apparatus provided in the support stand through the tray. In addition, each wafer is cooled down by a cold gas (such as helium gas) supplied from a cold gas supply pipe line provided in the support stand through the tray.